Correctly selected lenses create a more voluminous and better image on the retina of the eye, contribute to sharpening and widening the field of view, restore binocular vision, reduce the phenomenon of visual fatigue and increase visual performance.
Today the market presents several types of contact lenses, different in quality and service life. So the choice of the most optimal for each individual person can be difficult. Meanwhile, ophthalmologists have accumulated sufficient experience with such patients and offer a number of recommendations on the diagnosis and selection of soft contact lenses and their proper use.
To begin with, soft lenses tightly touch the corneal epithelium, which is very sensitive to lack of oxygen. The area of the limb (the area of access of the blood vessels to the cornea, the same dark groove that separates the cornea from the sclera) is the source of stem cells, which ensure the constant renewal of the corneal tissue. If contact lenses interfere with the cornea to get enough oxygen, it helps to disrupt its metabolism and integrity, reduce the thickness of the epithelium and other problems. Oxygen starvation of the cornea does not allow it to withstand bacteria and increases the risk of infection.
A new polymer material for soft contact lenses - silicone-hydrogel - has a high oxygen permeability with hydrophilic properties. Such lenses are better than others to preserve eye health.
In general, today there are the following types of lenses:
• from hydrogel with different water content (from 50 to 95%);
• from polymethylacrylic (PMMA);
• from copolymers of silicone.
Not only for correction
Many believe that soft contact lenses can replace glasses only with myopia (myopia). In fact, the range of indications for contact vision correction is much wider:
• anisometropia over 2 dpt;
• high degree of myopia and hypermetropia;
• aphakia;
• astigmatism (wrong and high degree);
• keratoconus.
Currently, contact lenses are used not only for vision correction, but also for medicinal purposes - as a protective and bandage device for inflammatory, dystrophic, traumatic diseases, in the postoperative period. Lenses can also be used for cosmetic purposes, for example, with iris defects, with total opacity of the cornea.
Contraindications
There are only two of them:
• inflammatory diseases of the cornea and conjunctiva;
• Individual intolerance. Unfortunately, at present, the number of people who, for these reasons, can not use soft lenses, is increasing.
There are factors that affect the tolerability of contact lenses and increase the risk of complications. It:
- common diseases of the body (diabetes, avitaminosis);
- Low level of hygiene, inappropriate conditions of life and production (air conditioning, air pollution, allergens), climate;
- type of contact lens (low gas permeability of the lens, improper selection, low quality or damage to the lens);
- the duration of wearing and the period of replacement of lenses;
- means for the care of contact lenses (toxic and allergic action of the components of solutions, violation of the recommendations for the care of lenses).
As you can see, for some factors a person can not influence, but most of them are quite controllable.
Different wearing modes
There is no single mode for all types of lenses to use them. It is always indicated in the instructions for use, and it must be strictly observed. In the traditional mode, you must always remove the lens at night. Recommended daily cleaning according to the instructions and enzymatic cleaning once a week.
With a scheduled replacement, one pair wears 3 months, cleaning according to the instructions. Despite the fact that this mode allows for the different types of lenses the duration of their continuous wearing up to 48 hours or more, my medical experience shows that it is better to take them off at night. This is a bit more troublesome, but there is less risk of complications.
With frequent scheduled replacement, a pair of lenses are used from 2 weeks to 1 month. Shoot in the evening, but you can leave 2-3 times a month for the night. This regime is especially popular abroad. He is the most sparing for the eyes. Preference in the diagnosis and selection of soft contact lenses should be given to contact lenses of short replacement times.
Complications
1. Redness of the eyeball (in the medical language - injection of the vessels of the eyeball).
It is accompanied by dryness, burning, itching, fatigue of the eye. Discomfort from contact lenses intensifies toward the end of the day, especially under unfavorable external conditions (dustiness, air conditioning, central heating), as well as with intense eye strain, working at the computer.
The causes can be: damaged lens edges, corneal hypoxia, tear production decrease and tear film dysfunction, reaction to a lens care solution or a chemical on the lens, and microbial toxins.
What to do?
• Eliminate the possible causes of complications (replacement of a contact lens or solution);
• apply wetting / lubricating drops intended for people who wear contact lenses. (There are substitutes for tears that can damage the lens - they do not fit!)
2. Limb hyperemia (redness around the cornea, in the limb zone).
Occurs, as a rule, when wearing soft contact lenses from hydrogels. The cause may be the corneal hypoxia caused by insufficient gas permeability or a dense "landing" of the contact lens on the cornea.
What to do?
• Use lenses with large gas permeability - silicone-hydrogel or other construction;
• Reduce the time of wearing the lens during the day.
3. Epitheliopathy of the cornea - superficial epithelial lesions, in which the sensation of a foreign body, dry eyes can occur.
What to do?
• 3-4 days of rest from the lenses;
• Bury antiseptic eye drops and stimulators of corneal regeneration 2-3 times a day;
• replacement of the type of lens or storage solution;
• Use wetting drops for people who wear contact lenses.
4. Edema and neovascularization of the cornea
It is accompanied by structural changes in the layers of the cornea, which can be detected by a physician in a biomicroscopic study. Corneal edema leads to blurred vision and decreased vision, worsening the tolerability of contact lenses. The reason is insufficient supply of cornea with oxygen, for example, in cases where the lens is not removed at night, when the lens material dries.
Vascularization is a compensatory mechanism for chronic edema of the cornea. Complication for a long time occurs without subjective symptoms and is detected by a control biomicroscopic examination of the patient. With prolonged course, the complication can lead to a violation of the transparency of the cornea and reduced vision.
What to do?
• use lenses with high gas permeability (silicone-hydrogel);
• Reduce the period of wearing the lens during the day;
• Bury wetting drops for contact lenses;
• In the case of persistent vascularization of the cornea, rigid gas permeable lenses must be worn.
5. Follicular conjunctivitis.
When the dirty lens is worn for a long time (with poor care of it), an immune response occurs to the products of the breakdown of proteins that accumulate under the lens.
What to do?
• give up contact lenses;
• Bury special eye drops to stabilize the membranes of mast cells 2 times a day;
• with acute course - antihistamines, with burning - preparations of artificial tears;
• replacement of storage solution;
• It is possible to use disposable lenses.
6. Syndrome of "dry eye"
There are complaints of redness, sensations of eye irritation, blurred vision.
What to do?
• replacement of the lens type;
• use of wetting / lubricating drops for contact lenses;
• with a decrease in tear production - preparations of artificial tears.
Prevention of complications
When diagnosing and selecting soft contact lenses, you must be careful. But later "relax" should not be. To avoid complications, the following rules must be observed.
1. Once every six months - a preventive visit to the polyclinic, to the ophthalmologist. It must be remembered that some complications develop without pain and unnoticeably.
2. Proper hygiene of contact lenses is necessary: cleaning taking into account the material of their manufacture, disinfection, moistening of the lens, storage in special containers. Change the container should be at least 1 time in 3-4 months.
3. Do not wear soft contact lenses for several days without taking off. It may be dangerous.
4. The lens should be either on the eye or in a container in a special storage solution. Otherwise, it will dry, it will have microcracks, which will soon make the lens unusable.
5. Do not wet the lens with saliva. In the saliva there is a large number of bacteria that can cause inflammatory diseases of the eyes.